1. Field of the Invention
The present invention relates to a lens shutter mechanism.
2. Description of the Related Art
In a known lens shutter mechanism for opening and closing a photographing aperture, provided in a compact camera or the like, in general, the shutter mechanism is supported between front and rear support frames that are spaced apart in the optical axis direction. The lens shutter mechanism includes light intercepting members (sectors or blades), which are moved into and retracted from the photographing aperture, and a drive ring which drives the light intercepting members.
It is necessary to prevent leakage of harmful light from the periphery of the shutter mechanism toward the outer peripheral side of the support frames. In an arrangement in which drive force is transmitted from outside the support frames to the drive ring, an opening is formed on the outer peripheral portion of the support frames to transmit the drive force. This opening makes it difficult to intercept light completely. In a known light interception device for a lens-shutter unit, light interception tapes are attached or adhered to the outer peripheries of the support frames. However, there is a chance that the adhesive of the light interception tape sticks to the light interception members or the drive ring, etc., thus resulting in failure of correct operation thereof.
Moreover, in a known lens shutter mechanism in which a shutter and a diaphragm are provided adjacent to each other in the optical axial direction, the two separate light intercepting members provided in the support frames increase the number of movable members. Consequently, the adhesion of the light interception tapes without interfering with the operation of the movable members is more difficult.
Furthermore, a rotation support portion of the drive ring is supported by a support frame. If the shutter drive ring and the diaphragm drive ring are separately provided, the support structure of the respective drive rings is complicated, thus resulting in an increase in the size of the lens shutter mechanism.
The present invention provides a simple and small lens shutter mechanism in which the surrounding components of a shutter can be reliably intercepted from harmful light.
For example, in an embodiment, a lens shutter mechanism includes, between front and rear support frames spaced in an optical axis direction and having photographing apertures, shutter sectors which open and close the photographing apertures, a shutter drive ring which is rotatable about the optical axis to drive the shutter sectors, diaphragm sectors which change an aperture diameter of the photographing apertures independently of the shutter sectors, and a diaphragm drive ring which is rotatable about the optical axis to drive the diaphragm sectors. The shutter drive ring and the diaphragm drive ring are located at different radial positions and at the same position in the optical axis direction. One and the other of the shutter drive ring and the diaphragm drive ring is provided with an inner flange and an outer flange respectively, the inner flange and the outer flange projecting in a radial direction toward each other so as to overlap in the axial direction, and engaging so as to be relatively slidable in the circumferential direction.
An axial position of one of the shutter drive ring and diaphragm drive ring can be determined in accordance with an engagement thereof with the front and rear support frames. An axial position of the other of the shutter drive ring and diaphragm drive ring can determined in accordance with an engagement thereof with one of the front and rear support frames and in accordance with an engagement thereof between the inner flange and the outer flange.
The lens shutter mechanism can further include an opening between the front and rear support frames, which extends form the inner diameter side to the outer diameter side of the front and rear support frames. One of the shutter drive ring and the diaphragm drive ring, which is positioned at an outer radial position with respect to the other of the shutter drive ring and the diaphragm drive ring, can be provided with a fitting portion which is fitted in the opening in order to cover the opening, the fitting portion being movable in the circumferential direction.
One of the front and rear support frames can be provided on the outer peripheral edge thereof with an outer peripheral wall portion which projects in the optical axis direction close to the other of the front and rear support frames. The one of the shutter drive ring and the diaphragm drive ring, having the fitting portion, partly overlaps the outer peripheral wall portion in the radial direction to cover the opening together with the outer peripheral wall portion.
The lens shutter mechanism can further include a driven projection provided on the fitting portion of the one of the shutter drive ring and the diaphragm drive ring, the driven projection extending outwardly from the opening in the radial direction; and a rotational force providing device provided outside the front and rear support frames, which engages with the driven projection to cause the one of the shutter drive ring and the diaphragm drive ring to rotate.
The lens shutter mechanism can be provided in a zoom lens, and the rotational force providing device can provide rotation to the driven projection in accordance with a zooming operation of the zoom lens to thereby rotate the one of the shutter drive ring and the diaphragm drive ring which includes the driven projection.
One of the front and rear support frames can be provided with a motor drive gear which projects from a surface thereof opposed to the other of the front and rear support frames, the motor drive gear being driven by a motor. The other of the shutter drive ring and the diaphragm shutter drive ring, which is positioned at an inner radial position, is provided on the outer peripheral surface thereof with a gear which engages with the motor drive gear. A radial space in which the motor drive gear is accommodated can be provided between the shutter drive ring and the diaphragm drive ring.
The motor can be controlled by a controller, to change the angular displacement and the rotation speed of the drive ring having the gear which engages with the motor drive gear.
The diaphragm drive ring can be located at an outer radial position with respect to the shutter drive ring, the diaphragm drive ring being provided with the inner flange on an inner peripheral surface thereof, and the shutter drive ring being provided with the outer flange on an outer peripheral surface thereof.
In another embodiment, a lens shutter mechanism includes, between front and rear support frames spaced in an optical axis direction and having photographing apertures, shutter sectors which open and close the photographing apertures, a shutter drive ring which is rotated about the optical axis to drive the shutter sectors, diaphragm sectors which change an aperture diameter of the photographing apertures independently of the shutter sectors, and a diaphragm drive ring which is rotated about the optical axis to drive the diaphragm sectors. The shutter drive ring and the diaphragm drive ring are located at different radial positions and at the same position in the optical axis direction, so that the shutter drive ring is located at an inner radial position and the diaphragm drive ring is located at an outer radial position. The diaphragm drive ring is provided with an inner flange which projects inwardly in the radial direction, and the shutter drive ring is provided with an outer flange which projects outwardly in the radial direction, the inner flange and the outer flange overlapping in the axial direction and engaging so as to be relatively slidable in the circumferential direction.
An axial position of the diaphragm drive ring can be determined in accordance with an engagement thereof with the front and rear support frames. An axial position of the shutter drive ring can be determined in accordance with an engagement thereof with one of the front and rear support frames and in accordance with an engagement thereof between the inner flange and the outer flange.
The lens shutter mechanism can further include an opening between the front and rear support frames, which extends form the inner diameter side to the outer diameter side of the front and rear support frames. The diaphragm drive ring can be provided with a fitting portion which is fitted in the opening in order to cover the opening, the fitting portion being movable in the circumferential direction.
One of the front and rear support frames can be provided on the outer peripheral edge thereof with an outer peripheral wall portion which projects in the optical axis direction close to the other of the front and rear support frames. The diaphragm drive ring partly overlaps the outer peripheral wall portion in the radial direction to cover the opening together with the outer peripheral wall portion.
The lens shutter mechanism can further include a driven projection provided on the fitting portion of the diaphragm drive ring, the driven projection extending outwardly from the opening in a radial direction; and a rotational force providing device provided outside the front and rear support frames, which engages with the driven projection to cause the diaphragm drive ring to rotate.
The lens shutter mechanism can be provided in a zoom lens, and the rotational force providing device can provide rotation to the driven projection in accordance with a zooming operation of the zoom lens to thereby rotate the diaphragm drive ring.
One of the front and rear support frames can be provided with a motor drive gear which projects from a surface thereof opposed to the other of the front and rear support frames, the motor drive gear being driven by a motor. The shutter drive ring can be provided on the outer peripheral surface thereof with a gear which engages with the motor drive gear. A radial space in which the motor drive gear is accommodated can be provided between the shutter drive ring and the diaphragm drive ring.
The motor can be controlled by a controller, to change the angular displacement and the rotation speed of the shutter drive ring.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 2001-81608 (filed on Mar. 21, 2001) which is expressly incorporated herein by reference in its entirety.